Set up your website and offers in the way you think will convert the most. Do a test run with Adwords or whatever method you use to get targeted traffic for 100 clicks. If 3 people convert out of 100, you have a 3% conversion rate.

If you're happy with the percentage, try a test with 1000 clicks. If you consistently get the same conversion rate, then you can estimate for the future with those numbers. You really can't estimate until you have done some testing first. Then you can start testing to improve that ratio.

Tweak something about your offer and then do another test run. Does it get a better conversion or worse? If it's better, then go with it. Tweak again, test again. Never be satisfied with your current conversion because there is almost always improvement that can be made.